Affinity chromatography has found wide application in the purification of various biologically active materials, including for example, enzymes, proteins, antibodies, nucleotides, small ligands, and the like. It is known that certain polysaccharide matrices comprise the most useful solid supports for affinity chromatography. Various methods exist to activate a polysaccharide matrix, e.g., cellulose, starch, and various crosslinked polysaccharide gels such as agarose, Sephadex.RTM. and Sepharose.RTM., for the covalent attachment of, e.g., small ligands and proteins. A widely used technique for the covalent coupling of, say, protein to insoluble matrices, finding considerable application in immunology and enzymology, is the cyanogen bromide method described in Axen et al, Nature, 214, 1302-4 (1967); see also Cuatrecasas et al, Proc. Natl. Acad. Sci. U.S., 61, 636-43 (1968). Another useful activation method described by Cuatrecasas et al in U.S. Pat. No. 3,947,352, issued Mar. 30, 1976 comprises sodium periodate oxidation followed by reductive amination using sodium borohydride or sodium cyanoborohydride.
The use of activated polysaccharides having ligands attached to purify biologically active material has been found a powerful laboratory tool. However, affinity chromatography using these materials is time consuming, especially when larger volumes, i.e., more than a liter, are desired to be purified because these materials produce columns having slow flow rates. One way to obtain faster flow rates is to attach a monolayer of a polysaccharide to an inorganic support, such as a glass bead, as described in U.S. Pat. No. 4,006,059, issued Feb. 1, 1977 to Butler or in U.S. Pat. No. 3,983,299, issued Sept. 28, 1976 to Regnier. These patents describe the attachment of a monolayer of dextran, starch, glycerol, etc. to an inorganic bead. The resultant chromatographic material has much improved flow rates over the activated polysaccharides described above. However, we have found that these materials having a monolayer of polysaccharide attached to an inorganic bead do not provide as high a degree of purification as desired (see examples herein). Thus it would be desirable to have a chromatographic material that provides columns with high flow rates and that also provides a high degree of purification.